The invention relates to a magnetic head having a head face and comprising a multilayer structure with a flux guide, a magnetoresistive sensor and an intermediate layer of an insulating oxide present between the flux guide and said sensor.
A magnetic head of this type is known from Funkschau 24/1988, pp. 37-40 "Mit Dunnschichtkopfen in neue Dimensionen" Mathias Krogmann. The known magnetic head has a head face for cooperation with a magnetic recording medium and is also provided with a magnetic yoke which comprises a magnetoresistive sensor and flux guides. The magnetic yoke adjoins the head face, while said sensor is spaced apart therefrom. The magnetoresistive sensor comprises a strip-shaped element of a magnetoresistive material. When the recording medium is being scanned, the magnetic yoke is in its immediate vicinity, or is in contact with, the recording medium moving with respect to the magnetic head. Information-representing magnetic fields of the recording medium then cause changes in the magnetization of the strip-shaped element and modulate its resistance due to the effect referred to as the magnetoresistive effect. This effect implies that, due to magnetic fields, the direction of magnetization in the magnetoresistive sensor rotates, at which the electrical resistance changes. These resistance changes may be measured by a suitable detection system and converted into an output signal which is a function of the information stored in the recording medium.
Since the change of the electrical resistance of a magnetoresistive element under the influence of an external magnetic field is quadratic in this field, it is common practice to improve the operation of the magnetic head by linearizing the resistance-magnetic field characteristic. To this end, the magnetoresistive element is biased in such a way that the direction of magnetization at a signal field which is equal to zero extends at an angle of approximately 45.degree. to the direction of the sense current through the element. In the known magnetoresistive sensor, this is realized by using an easy axis of magnetization which is parallel or substantially parallel to the longitudinal axis of the magnetoresistive element, and by an electric biasing which is achieved by means of equipotential strips of satisfactorily conducting material on the element, which strips cause a current direction at an angle of approximately 45.degree. to the longitudinal axis of the element. The known magnetic head further has a bias winding for generating a magnetic auxiliary field parallel to the plane of the strip-shaped element and perpendicular to the easy axis of magnetization. By means of the auxiliary field, fields which are due to the sense current and influence the angle between current and magnetization, and other disturbances of the optimum angle between current and magnetization can be compensated.
Starting from a ferrite substrate, the known magnetic head is built up in layers. During manufacture, the bias winding, the magnetoresistive element, the equipotential strips and the flux guides are formed successively, while SiO.sub.2 layers are provided between the substrate and the bias winding, between the bias winding and the magnetoresistive element and between the magnetoresistive element and the flux guides. These layers are required to insulate various electrically conducting layers in order to inhibit short circuits.
The known magnetic head is necessarily composed of a relatively large number of layers. This has the drawback that the manufacture of the known magnetic head is cumbersome due to the large number of deposition and structuring steps to be performed, so that the manufacturing process is time consuming and costly.